Process for producing aminoalkylsilanes



3,45,Z95 Patented July 24, 1962 ace This invention relates to a processfor producing aminoalkylsilanes. More particularly, the invention isdirected to a process for producing N-(aminoalkyl)aminoalkylsilanes.

The process of this invention comprises contacting under essentiallyanhydrous conditions a cyanoalkylalkoxysilane with a diamino compound, ahydrogenation catalyst and hydrogen under pressure. For example, betacyanoethylmethyldiethoxysilane is contacted with dry ethylene diamine,Raney nickel catalyst, and hydrogen at 1000 pounds per square inch gaugeto produce N-(betaaminoethyl)-gamma aminopropylmethyldiethoxysilane, HNCH CH NHCH CH CH Si CH OC H Anhydrous conditions are advantageous inproducing N-( aminoalkyl) aminoalkylsilicon compounds by the process ofthis invention. If water is present in an amount greater than about 2weight percent (based on the amount of diamino compound) gelation of thereaction mixture takes place and the yield of the desired product issharply reduced.

The cyanoalkylsilanes useful in the process of the present invention maybe represented by the formula:

No 112 SlAa-b wherein R is a monovalent hydrocarbon group free fromaliphatic unsaturation such as alkyl, cycloalkyl, aryl, alkaryl andaralkyl and preferably containing from 1 to carbon atoms, A is an alkoxygroup, preferably an alkoxy group containing from 1 to 8 carbon atoms, ais an integer having a value from 2 to 5, b is an integer having a valuefrom zero to 1 and the cyano group is removed from the silicon atom byat least two carbon atoms.

Illustrative of the useful silanes represented by Formula A are thefollowing:

A preferred class of cyanoalkylalkoxysilanes are those wherein the C l-lgroup of Formula A has the structure -CH CH Thesebeta-cyanoethylalkoxysilanes are preferred because they are easilyprepared in high yield by the method described in the next paragraphhereinbelow.

The cyanoalkylalkoxysilanes represented by Formula A may be prepared byreacting a cyano aliphatic compound containing a double bond with achlorosilane having the formula Rb HS lcl3b wherein R and b have themeanings defined hereinabove with reference to Formula A, in thepresence of a conventional platinum catalyst or tri(monovalenthydrocarbon) phosphine catalyst, followed by esterification of theresulting cyanoalkylchlorosilane to give a silane of Formula A. Forexample, using triphenylphosphine catalyst, acrylonitrile reacts withtrichlorosilane to produce betacyanoethyltrichlorosilane, and using aplatinum catalyst in each instance, methacrylonitrile reacts Withphenyldichlorosilane to produce beta-cyanopropylphenyldichloro silaneand allylcyanide reacts with methyldichlorosilane to producegamma-cyanopropylmethyldichlorosilane. The corresponding alkoxysilanesare obtained by esterification.

The cyanoalkylalkoxysilanes useful in the present invention may also beproduced by reacting a chloroalkylalkoxysilane with sodium cyanide inN,N-dirnethylformamide (DMF) solvent. For example, sodium cyanide andgamma-chicropropylphenyldiethoxysilane react in DMF to producegamma-cyanopropylphenyldiethoxysilane, and sodium cyanide andgamma-chloro-beta,betaclimethylpropyltriethoxysilane react to producegammacyano-beta,beta-dimethylpropyltriethoxysilane.

Chloroalkylchlorosilanes, which can be converted tochloroalkylalltoxysilanes by conventional methods and thereafter reactedwith sodium cyanide to give compounds of Formula A, may be produced bythe direct chlorination of alkyl chlorosilanes. For example, chlorinereacts with n-propylphenyldichlorosilane in the presence of ultravioletlight to give gamma-chloropropylphenyldichlorosilane andneopentyltrichlorosilane reacts with chlorine in the presence of ultraviolet light to givegamma-chloro-beta,beta-dimethylpropyltrichlorosilane.

The diamino compounds useful in the process of this invention may berepresented by the formula:

HzN oiHzrN Formula B are the following:

Typical examples of the process of the present invention are thefollowing: the reaction of beta-cyano-npropyltriethoxysilane withethylene diamine and hydrogen to give N(beta-aminoethyl)gamma-aminoisobutyltriethoxysilane, the reaction ofbeta-cyanoethylmethyldiheptoxysilane with N,N-diethylethylene diamineand hydrogen to giveN'-(beta-N,N-diethylaminoethyl)-gamma-aminopropylmethyldiheptoxysilane,the reaction of beta-cyanoethylphenyldimethoxysilane withN-hydroxyethylethylene diamine and hydrogen to giveN'-(beta-N-hydroxyethylaminoethyl) -gammaaminopropylphenyldimethoxysilane, the reaction ofbeta-cyanoethylpropyldiethoxysilane with hexamethylene diamine( 1,6) andhydrogen to give N- (omega amino nhexyl)-gamma-aminopropylpropyldiethoxysilane, the reaction ofbeta-cyanoethyl(cyclohexyl)diethoxysilane with ethylene diamine andhydrogen to give N-(beta-aminoethyl)-gamma-aminopropylcyclo-,hexyldiethoxysilane and the reaction ofgamma-cyano-nbutyltriethoxysilane with tetraethylene pentamine andhydrogen to give All of these reactions are carried out under anhydrousconditions, in the presence of a hydrogenation catalyst, and with aninitial hydrogen pressure at temperature of at least 100 pounds persquare inch gauge.

The ratio of reactants in the process of this invention is not critical.However, unless at least one mole of diamino compound per mole ofcyanoalkylalkoxysilane is used yields of aminoalkylaminoalkylsilanes ofonly a few percent are obtained. The preferred mole ratio of diarninocompound to cyanoalkylsilane is from about 3-to-1 to about 10-to-1. Moleratios of 20-to-1 or higher are operable but no particular advantage isgained by employing mole ratios in excess of the 3-to-1 to 10-to-1range.

The process of this invention may be carried out with or without asolvent and no particular advantage is gained through the use of asolvent. In recovering the product from the final reaction mixture asolvent may be used to wash the product away from the catalyst. Ifdesired the cyanoalkylsilane and the diarnino compound may be mixedtogether in a solvent while being contacted with the catalyst andhydrogen. Any liquid organic solvent conventionally employed inreactions involving organosilicon compounds may be used. Examples ofsuitable solvents for the starting reaction mixture or for washing outthe catalyst are: aliphatic hydrocarbons such as hexane, heptane andpetroleum ether, alcohols such as ethanol, butanol and 2-ethylhexanoland aromatic hydrocarbons such as benzene, toluene and xylene.

The reaction temperature and time may vary over wide ranges. In general,temperatures in the range of from 50 C. to 300 C. are employed withtimes ranging from one hour to 24 hours. At lower temperatures thereaction proceeds slowly and at higher temperatures the yield may bereduced due to decomposition of one or more of the reactants orproducts. The preferred operating conditions were found to be from 145C. to 175 C. for 3 to 6 hours.

Any conventional hydrogenation catalyst can be employed. Examples ofsuitable catalysts are Raney nickel, Girdler nickel (finely-dividednickel on silica gel) and bis(cyclopentadienyl)nickel. The Girdlernickel catalyst has been found to be particularly suitable. The amountof catalyst employed is not critical. About to 10- weight percent ofcatalyst based on the amount of cyanoalkylsilicon compound represents aconvenient amount.

The hydrogen pressure at the operating temperature may vary over widelimits. It has been found that an initial hydrogen pressure at thereaction temperature of at least 100 p.s.i.g. is necessary for yields ofmore than a few percent. The upper limit of hydrogen pressure isdetermined by the strength of the equipment used and otherconsiderations of safety. The preferred initial hydrogen pressure attemperature is 1500 p.s.i.g. to 2500 p.s.i.g. As the hydrogenationproceeds, the initial pressure falls steadily as the reaction goes tocompletion. If the hydrogen pressure drops substantially before thereaction is complete, additional hydrogen may be added.

Because of the high pressure nature of the reaction, the process issuitably carried out in a pressure vessel such as a Paar bomb or anautoclave.

In order to obtain satisfactory yields by the process of this inventionit is necessary that the reaction be carried out under anhydrousconditions. The primary potential source of undesirable water is thediarnino compound. Consequently the diarnino compound should becarefully dried before use. This may be done conveniently bydistillation or by employing a suitable drying agent. It has been foundthat when the amount of water in the system exceeds about 2 weightpercent (based on the amount of diarnino reactant), gelation of thereaction mixture occurs and the yield of aminoalkylaminoalkyl compoundis seriously reduced.

It is also desirable to employ hydrogen gas which is substantiallyanhydrous. Relatively small amounts of water in hydrogen may interferewith the reaction since the concentration of hydrogen is relatively highat the pressures employed.

The compounds produced by the process of the pres- 1 ent invention areuseful as sizing agents for glass cloth which is used in the preparationof glass cloth laminates. The glass cloth prior to laminating may beimmersed in an aqueous or other solvent solution of theaminoalkylaminoalkylsilicon compounds of this invention. The glass clothis then removed from the treating solution, dried and dipped into a bathcontaining a thermosetting resin. Laminates are then prepared accordingto conventional procedures using the resin coated glass cloth and arecured at elevated temperatures. Suitable thermosetting resins arealdehyde condensation resins, epoxy resins and urethane resins.

In the detailed illustrative examples presented hereinbelow, thefollowing abbreviations are used:

wave length of the sodium D line. p.s.i.g. pounds per square inch gauge.

Example 1 A mixture of beta-cyanoethyltriethoxysilane (109 g., 113 ml0.5 mole), dry ethylene diamine g., ml., 1.5 mole) and 10 grams ofGirdler nickel catalyst was charged to a 300 ml. autoclave. The systemwas pressurized to 1850 p.s.i.g. with hydrogen. The vessel was heated to150 C. with rocking and the pressure dropped from 2200 p.s.i.g. to 350p.s.i.g. in one hour. The vessel was thereafter recharged four timeswith hydrogen to a pressure at temperature of about 1850 p.s.i.g. over a3.5 hour period and, during the 3.5 hour period, a total of 1150p.s.i.g. hydrogen pressure drop was observed. At this point, the vesselwas cooled to room temperature. The autoclave was vented in a hood andthe reaction mixture filtered under a nitrogen atmosphere. Xylene (100ml.) was used to wash out the autoclave and the washings Were filteredand combined with the first filtrate. The combined filtrate wasfractionally distilled under reduced pressure through an 18 inchinsulated Vigreaux column. By this distillationN(beta-aminoethyl)gammaaminopropyltriethoxysilane, [11 g., n;, 1.4365,boiled at 115124 C. (0.1-1.1 mm. Hg)] Was obtained in 10 mole-percentyield.

Example 2 Following the procedure of Example 1, dry ethylene diamine andbeta-cyano-n-propylrnethyldiethoxysilane in a mole ratio of 3-to-1 aremixed in a pressure vessel. Girdler nickel catalyst weight percent basedon the silane) is added and the system is pressurized with enoughhydrogen to give a pressure of about 2000 p.s.i.g. at 150 C. The vesselis then heated to about 150 C. and rocked at this temperature for fourhours. Additional hydrogen is added as needed as the reactionprogresses. The vessel is cooled to room temperature, opened and thecontents filtered in an inert atmosphere. N-(betaaminoethyl) gammaaminoisobutylmethyldiethoxysilane is then recovered from the fiiteredreaction mixture by fractional distillation under reduced pressure.

Example 3 A mixture of betacyanoethyltriethoxysilane (0.5 mole), dryethylene diamine (1.5 mole), 10 grams of Girdler nickel catalyst andgrams of sodium zeolite A pellets (drying agent) was charged to a 300m1. autoclave. The system was pressurized with hydrogen and heated to130 C. to 150 C. over a period of six hours at a maximum hydrogenpressure of 1950 p.s.i.g. Five separate additions of hydrogen were madeduring the 6 hour period, and the total pressure drop was about 4800p.s.i.g. The autoclave was vented and the reaction mixture was filteredunder a nitrogen atmosphere. Xylene (60 ml.) was used to wash out theautoclave and the washings were filtered and combined with the firstfiltrate. The combined filtrate was fractionally distilled under reducedpressure through an 18 inch insulated Vigreaux column, andN-(beta-aminoethyl)-gamma-aminopropyltriethoxysilane was recovered in 15mole percent yield.

Example 4 A mixture of beta cyanoethyltriethoxysilane (0.5 mole),ethylene diamine (about 1.5 mole) containing more than about 2 weightpercent water, and 5.5 grams of Girdler nickel catalyst was charged to a300 ml. autoclave. The autoclave was pressurized with hydrogen andheated according to the procedure described in Example 3. The principalproduct (77 grams) was a yellow-resinous mass. No distillableaminoalkylalkoxysilane Was recovered.

What is claimed is:

1. A process for producing N-(aminoalkyl)aminoalkylsilanes whichcomprises contacting under essentially anhydrous conditions and at atemperature between about 50 C. and 300 C. 1) a cyanoalkyl silanerepresented by the formula:

Rs Nc(c H2u)s iAa-b wherein R is a monovalent hydrocarbon group freefrom aliphatic unsaturation containing from 1 to 10 carbon atoms, A isan alkoxy group containing from 1 to 8 carbon atoms, a is an integerhaving a value from 2 to 5, b is an integer having a value from zero tol and the cyano group is removed from the silicon atom by at least twocarbon atoms, (2) a diamino compound represented by the formula:

G H2NO.H2.N

wherein r is an integer having a value from 2 to 6, the nitrogen atomsbonded to the C 11 group are separated by at least 2 carbon atoms, G isselected from the class consisting of hydrogen, beta-hydroxyethyl, alkylgroups having from 1 to 6 carbon atoms and (CH CH NH) H groups wherein sis an integer having a value from 1 to 5 3, and G is selected from theclass consisting of hydrogen, beta-aminoethyl, beta-hydroxyethyl, andalkyl groups having from 1 to 6 carbon atoms, (3) a hydrogenationcatalyst, and (4-) hydrogen at an initial pressure at temperature of atleast pounds per square inch gauge.

2. Process in accordance with claim 1 wherein said cyanoalkylsilane andsaid diamino compound are mixed together in a iiquid organic solvent.

3. A process for producing N-(aminoalkyl) -beta-aminoethylsilanes whichcomprise contacting under essentially anhydrous conditions and at atemperature between about 50 C. and 300 C. (l) a cyanoalkylsilanerepresented by the formula:

l s NC CHzCHzSiAs-b wherein R is a monovalent hydrocarbon group freefrom aliphatic unsaturation containing from 1 to 10 carbon atoms, A isan alkoxy group containing from 1 to 8 carbon atoms and b is an integerhaving a value from zero to 1, (2) a diamine compound represented by theformula:

HZNCrHZrN wherein r is an integer having a value from 2 to 6, thenitrogen atoms bonded to the C H group are separated by at least 2carbon atoms, G is selected from the class consisting of hydrogen,beta-hydroxyethyl, alkyl groups having from 1 to 6 carbon atoms and (CHCH NH) H groups wherein s is an integer having a value from 1 t0 3, andG is selected from the class consisting of hydrogen, beta-aminoethyl,beta-hydroxyethyl, and alkyl groups having from 1 to 6 carbon atoms, (3)a hydrogenation catalyst, and (4) hydrogen at an initial pressure attemperature of at least 100 pounds per square inch gauge.

4. Process in accordance With claim 3 wherein said cyanoalkylsilane andsaid diamino compound are mixed together in a liquid organic solvent.

5. Process in accordance with claim 3 wherein said temperature is fromabout C. to 175 C. and said hydrogen is at a pressure at temperature ofbetween about 1500 and 2500 pounds per square inch gauge.

6. Process in accordance with claim 3 wherein said hydrogenationcatalyst is finely divided nickel on silica gel.

7. A process for producingN-(beta-aminoethyD-gamma-aminopropyltriethoxysilane which comprisescontacting under essentially anhydrous conditions and at a temperatureof about C. beta-cyanoethyltriethoxysilane, ethylene diamine, finelydivided nickel on silica gel and hydrogen at an initial pressure attemperature of about 2200 pound per square inch gauge.

8. A process for producingN-(beta-aminoethyl)-gamma-aminoisobutyirnethyldiethoxysilane whichcomprises contacting under essentially anhydrous conditions and at atemperature or" about 150 C. beta-cyano-n-propylmethyldiethoxysilane,ethylene diamine, finely divided nickel on silica gel and hydrogen at aninitial pressure at temperature of about 2000 pounds per square inchgauge.

References Cited in the file of this patent UNITED STATES PATENTS2,876,209 De Benneville et a1 Mar. 3, 1959 2,930,809 Jex et al Mar. 29,1960 FOREIGN PATENTS 1,184,198 France Feb. 2, 1959

1. A PROCESS FOR PRODUCING N-(AMINOALKYL) AMINOALKYLSILANES WHICHCOMPRISES CONTACTING UNDER ESSENTIALLY ANHYDROUS CONDITIONS AND AT ATEMPERATURE BETWEEN ABOUT 50*C. AND 300*C. (1) A CYANOALKYL SILANEREPRESENTED BY THE FORMULA: